In the production of drinks such as fruit juices, nectars, still drinks (non-carbonated soft drinks) and the like, the intention is often to mix two or more flows of different characters with one another. Such mixtures may, for instance, consist of a mixture of a juice concentrate with water, sugar solution with a fruit juice, etc. After the mixing operation, the sugar content is measured in the product in Brix with the aid of a refractometer. In order that the Brix value of the product be as reliable as possible, the mixture must be as homogeneous as possible before the product reaches the refractometer.
Mixing can be put into effect in different ways. One method is batchwise mixing in a tank with agitators, this method being both expensive and requiring large areas of space. Another method is that the mixing operation takes place in a so-called static mixer, i.e. the two flows are forced to pass a device where a number of obliquely inclined plates or disks give rise to a turbulence in the flows and thereby a mixing of the flows. However, this method does not give an entirely reliable mixing and, when the flow reaches the refractometer for measuring the Brix value, the results obtained are not wholly satisfactory.
In most countries, juices and nectars have a stipulated minimum Brix value in order to be sold under each respective name. If there is incomplete mixing and thereby an unreliable Brix value in the subsequent measurement, it must be ensured that there is a margin to the lowest permitted Brix value, and this gives rise to increased raw materials costs in the production of specific products.
The flows in a mixing process of the above-described type also have large variations, depending upon the volume of the tanks, pump capacities and the like, for which reason it may be difficult using conventional mixing methods to obtain a reliable and efficient control of the production process.